Safety Relief Valve Location
Safety Relief Valve Location
(OP)
Hi guys,
I currently have a Nitrogen vessel that is 54"OD X 11' S/S, designed to 150psig @450F; it currently operates at 120psig @80F but it has a very difficult to get relief valve on the top of the vessel. We are thinking of relocating the valve to the side of the vessel since there is a plug on the side of that we could use. I have read that the Best Engineering practice is to keep the valve on top of the vessel but I haven't found anything that prevent's me from relocating the relief valve to the side. I don't have have a lot of experience with relief valves and pressure vessels so your feedback is greatly appreciated.
Thanks,
Sal
I currently have a Nitrogen vessel that is 54"OD X 11' S/S, designed to 150psig @450F; it currently operates at 120psig @80F but it has a very difficult to get relief valve on the top of the vessel. We are thinking of relocating the valve to the side of the vessel since there is a plug on the side of that we could use. I have read that the Best Engineering practice is to keep the valve on top of the vessel but I haven't found anything that prevent's me from relocating the relief valve to the side. I don't have have a lot of experience with relief valves and pressure vessels so your feedback is greatly appreciated.
Thanks,
Sal





RE: Safety Relief Valve Location
RE: Safety Relief Valve Location
What is the length of the skirt or support legs?
Does this vessel have a Platform on top (if not why not)?
Does this vessel have a ladder up the side to the top?
What else is on the top of this vessel?
What is the maximum liquid level possible for this vessel?
Where is the 'side' nozzle in relation to the maximum liquid level?
Where does the PSV discharge to (a closed system or atmosphere)?
Sometimes its possible to do all the right things and still get bad results
RE: Safety Relief Valve Location
As pennpiper pointed out, you need to look at other things as well - if there is a potential for liquids to flood the PSV nozzle, or if PSV reliefs to atmosphere, then additional measures need to be taken to ensure the PSV will perform as intended.
Dejan IVANOVIC
Process Engineer, MSChE
RE: Safety Relief Valve Location
Thanks for the reply.
This vessel does not have a platform on top, I don't know why it was designed like that; It also does not have a ladder up the side to the top. We have to bring a lift every time we inspect the valve or replace it. There is nothing else in top of the vessel other then process piping that makes access to the relief valve with man lift somewhat difficult but not impossible.
As far as liquid goes, we don't expect to see any liquid in the tank plus we don't have any level sensors in that tank. However, the side nozzle that we are planning on using is at the same height as the inlet coming from the Desiccant dryer; which is about 5ft above the tank lowest level.
This PSV discharges to the atmosphere. Which may pose another concern on the safety side; If the valve happens to discharge while somebody is standing next to the vessel...
Thanks for your replies, I really appreciate your feedback.
RE: Safety Relief Valve Location
I hope this vessel is outdoors otherwise Nitrogen direct to atmosphere sounds a bit risky...
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Safety Relief Valve Location
RE: Safety Relief Valve Location
For nitrogen at the conditions you state, I don't expect to see liquid either, unless there is something else present besides nitrogen.
The concern I would have would arise because the PSV is going to atmosphere. It might or might not be a big deal, depending on the size(s) involved, but double check the reaction forces created when the PSV lifts, and support the pipe accordingly to prevent overloading the nozzle.
RE: Safety Relief Valve Location
RE: Safety Relief Valve Location
JAC
RE: Safety Relief Valve Location
Per ISO, only the term Safety Valve is used for all overpressure eventualities regardless of design.
RE: Safety Relief Valve Location
JAC
RE: Safety Relief Valve Location
Per ISO, only the term Safety Valve is used for all overpressure eventualities regardless of design.